In our today’s comparative article we are going to discuss two controllers from Promise and HighPoint and investigate one of their most interesting features: performance of degraded RAID 5 and RAID 6 arrays.

The controllers were installed into 64-bit 100MHz PCI-X and PCI Express x8 slots depending on their interface.

The Western Digital WD740GD (Raptor 2) hard disks were installed into the standard boxes of the SC5200 system case. The controllers were tested with four HDDs in the following modes:

RAID0 (with two, three and four HDDs)

RAID1 (with two HDDs)

RAID10 (with four HDDs)

RAID5 (with three and four HDDs and with four HDDs in degraded mode)

RAID6 (with four HDDs and in degraded mode with one or two failed HDDs)

The controller was set at the Performance mode for maximum performance during the tests. This mode allows deferred writing and look-ahead reading for both the controller (in its own buffer memory) and the disks. The Performance mode should not be used without a cache battery because there is a high risk of losing data in case of a power failure.